The military has two obvious uses for a UAV—as a weapons platform and for reconnaissance. The forward observer has always been a problem. If he is close enough to see everything, he is also close enough to be discovered and attacked. As the action heats up the reliability and frequency of his observations go down. The solution to these problems is a UAV carrying a sensor package; a solution that has long been recognized. By putting the pilot/observer at some distance from the target, he can be kept safe. At the same time his observations are essentially from close range and can therefore be very reliable. Because he is not in immediate danger he can remain on station for some time and continue reporting.
The question then is not the value of an UAV, but rather, how to make one small and inexpensive, yet still able to perform useful missions.
Flying wings have obvious advantages and have been an intriguing prospect for many years. Their basic problem is that they are only marginally stable in pitch. (They are also less than terrific in yaw, but this deficiency can be accommodated by increased dihedral.) In the '50s Northrop built several. Their poor stability characteristics made them difficult to fly and they never lived up to promise.
A flying wing needs stability augmentation. But in the early days, stability augmentation technology was immature. With the development of missiles in the '60s and '70s the technology improved dramatically. (Many missiles have neutral or slightly negative stability during some portion of their flight.) Autopilots were developed that utilized rate gyros for feedback in servo controlled systems. The performance of the gyros improved (they became smaller, more accurate and dependable). Electronics evolved from vacuum tubes to solid state technology with dramatic improvements in size, power consumption and reliability. In short, stability augmentation became a mature technology.
But a return to flying wing development didn't happen. Perhaps because its champion, Jack Northrop, died. And perhaps because there is a reluctance to depend on an active device for the aircraft's basic safety if such can be avoided. This is a powerful argument when lives are at stake. It should not, however, be a deterrent for an unmanned aircraft.
The Wrights included wing warping among their control devices. Later, with the introduction of metal wing construction it was abandoned. Conventional metal wings are very stiff in torsion; a property arising from their box beam design and from the high shear stiffness of the metal. Composite structures also have considerable torsional stiffness, depending primarily on the matrix material. Fabrics however have, in themselves, very little shear stiffness. The wing will therefore be very responsive to the controls. That is, there will be a maximum twist per pound of pull on the control cables. Vehicle response (Gs/pound of pull on the control cables) will therefore be high, the control power required low.